Immunity for knockback

When we tried to implement immunity for knockback for all bosses and vehicles, rsa reverted it saying that it is wrong. Maybe we should add a flag for this immunity?This is a big problem in game, knocking bosses may lead to exploiting, knocking vehicles in bg leads to unfair winning etc.

I don't know if there are any bits left in mechanic_immunity_mask, if not then maybe in flags_extra?

Full knockback immunity impossible (some units with "boss" parameters, also some vehicles be knockbacked, it's fact), need research for this. possible some flags? if no one flag - need make custom flag.

I think this is just an enum named in a wrong way. It isn't related anyhow to spell effect knockup/knockback/etc. so using this flag would lead to unwanted immunities/vulnerabilities. Must add new flag.